Eupatorium is a genus of flowering plants, part of the enormous aster family. Perfoliatum means perforated, referring to the fact that the stem appears to
grow through opposing pairs of adjoined leaves. The common name, boneset, derives from
the plant's use at one time in treating dengue fever, which was also known as breakbone.
Identification: Plants reach 3′ (1 m) high. The
stout, very hairy stem branches at the top to support the flowers. Leaves are up to 8″ (20 cm) long,
long and narrow, with pointed ends and fine serrations. Prominent veins produce a rough upper surface
and a hairy, somewhat sticky lower surface.
Opposite leaf pairs are joined around the stem ("connate"), so that the stem appears to be growing through them, a major
identifying trait. Small, dull white (sometimes pinkish) flowers emerge in flat-topped or slightly dome-shaped clusters at the
top of the stem, which branches to support multiple clusters. Individual flowers are about ⅛″ (3 mm)
in diameter. The flowers lack petals ("rays") and look like tiny shaving brushes.
Medical: Boneset has a long and often dubious history of
medicinal use. Its opposite pairs of joined leaves were once thought to signify the power to heal
broken bones. It was used to treat dengue fever. It was also used as a stimulant, and a laxative.
Leaves brewed into a tea have been used to reduce fever, its primary use. There is no evidence to
support any of these uses, and some evidence of mild toxicity—plants "should not be ingested."
Small, dull white (sometimes pinkish) flowers are flat-topped or slightly dome-shaped clusters. Individual flowers are about ⅛″ (3 mm) in diameter. The flowers lack petals ("rays") and look like tiny shaving brushes.
Leaves
Opposite leaf pairs are joined around the stem, so that the stem appears to be growing through them. Leaves are up to 8″ (20 cm) long, long and narrow, with pointed ends and fine serrations. Prominent veins produce a rough upper surface and a hairy, somewhat sticky lower surface.
Stem
The stout, very hairy stem branches at the top to support the flowers.
Plants are 3-5′ (91-152 cm) high, and up to 3′ (91 cm) around, with single or multiple stems.
Flowers
Flowerheads are somewhat dome-shaped clusters, each with 10-30 white brushlike flowers with no petals. Each flower is about ⅛″ (4 mm) around.
Leaves
Leaves are 2-5″ (5-12 cm) long, lance-shaped, and tapering at both ends; lower leaves are broader, more heart-shaped. Each leaf has three prominent veins and serrated edges. Leaf stems (petioles) are ½-1½″ (1.3-3.8 cm) long. Leaves are darker in the 'Chocolate' cultivar.